close quarters, at/in

Crowded, in a confined space. The term comes from eighteenth-century naval warfare. Wooden barriers were placed at vari- ous points on a ship, so that when an enemy boarded, the crew could retreat behind them and fire at the enemy through loopholes. The crew then were said to be fighting in close quarters, that is, in close contact with the enemy. The term later was transferred to any close contact or crowded situation